In this presentation, two examples of the influence of organic layers morphology on device performance will be discussed.We have been studying the role of phenanthrolines (BPhen and BCP) as electron-extraction layers on the performance of organic photovoltaics. In particular, we found that both materials grow as nanostructured layers, with columnar grain-like structures, with pillars having heights much larger than the average layer thickness. Yet, we found that the presence of such interlayers, in combination with LiF/Al electrodes, leads to significant efficiency improvements.The second part is devoted to the study of light-emitting diodes based on polymer blends, which combine polymers with efficient energy transfer. We found that the use of a solvent additive leads to a suppression of that energy transfer process, which we attribute to changes in the blend film morphology.